In tropical and sub-tropical climates, retractable, roll-down storm shutters provide effective and convenient protection from damage caused by wind-driven rain. When fully retracted, roll-down storm shutters let in sunshine and fresh air and provide a view. When fully closed, they keep wind-driven rain out. Many homeowners in these climates depend on retractable storm shutters to protect furniture, flowering plants and other valuable articles on their screened-in porches and lanais from damage caused by seasonal rain storms. Typical homeowners prefer to leave their storm shutters up while they are at home to enjoy the daylight and view that screened porches and lanais provide. They would also benefit from having their storm shutters close automatically if a rain shower occurred while they were asleep or away from home and were unable to lower them manually. Current retractable roll-down shutters can be manually raised or lowered by means of a hand crank or they can be raised and lowered by electric motors that are controlled by manual wall switches inside the home or by wall mounted or handheld radio frequency remote controllers.
Rain sensors presently available for use with electric storm shutters have not been commercially successful for several reasons.
One existing system, designed for extending and retracting a single awning, has been modified to control a single storm shutter. This system comprises an electronic module installed on a wall inside the house which can control one drive motor. It contains low-voltage connections to which rain, wind and/or sun sensors may be attached, and power connections for connecting the control system to 120 VAC mains. The unit includes one wall switch for manual control of one drive motor. If it is required to control two or more shutters using this system, an additional power module must be mounted in a weatherproof enclosure near the shutter drive motor power connections on the porch or lanais. If it is desired to retain individual manual control of the shutter motors will wall-mounted switches, two additional unswitched wires (120 VAC and Neutral) must be routed to the power module in addition to three wires for each wall switch. Additionally, if it is desired to use more than one rain sensor with this system, an external 12 VAC power supply must be added. This control system contains a microprocessor that must be programmed in order for it to function properly. The rain sensors are not programmable via the electronic control module, but have adjustable settings inside the sensors, which include discrete levels of sensitivity to moisture and adjustable delay times to react to detected moisture.
In another existing system, also designed for awning control, but conceivably adaptable to electric storm shutters, the rain sensor requires 230 VAC and draws 30 millimeters of current. Its power supply requirement severely limits the placement of these sensors to locations where 230 VAC is readily available or easily routed, an unlikely situation in US residential applications.